Investigation of native isolates of entomopathogenic fungi for the biological control of three citrus pests

The pathogenicity of 15 isolates of Beauveria bassiana (Balsamo) Vuillemin, five isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and one isolate of M. flavoviride (Gams and Rozsypal) were tested under laboratory conditions against the subterranean life stages of the citrus pests, Ceratitis rosa Karsch, C. capitata Wiedemann (Diptera: Tephritidae) and Thaumatotibia leucotreta Meyrick. (Lepidoptera: Tortricidae). When these citrus pests were treated with a concentration of 1×10⁷ conidia mL^?1, fungal isolates had a significantly greater effect on the adults of C. rosa and C. capitata than they did on the puparia of these two fruit fly species. Further, C. rosa and C. capitata did not differ significantly in their response to entomopathogenic fungi when adult and pupal mycosis were considered. Depending on fungal isolate, the percentage of T. leucotreta adults which emerged from fungal treated sand ranged from 5 to 60% and the percentage of pupae with visible signs of mycosis ranged from 21 to 93%. The relative virulence of the four most promising fungal isolates, as well as the commercially available B. bassiana product, BroadBand® (Biological Control Products, South Africa), were compared against one another as log-probit regressions of mortality against T. leucotreta which exhibited a dose-dependent response. The estimated LC₅₀ values of the three most virulent B. bassiana isolates ranged from 6.8×10⁵ to 2.1×10⁶ conidia mL^?1, while those of the least pathogenic ranged from 1.6×10⁷ to 3.7×10⁷ conidia mL^?1.     

Efficacy of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against Thaumetopoea pityocampa Shiff. (Lepidoptera: Thaumatopoeidae)

Abstract

In this study, Metarhizium anisopliae TR 106 and Beauveria bassiana TR 217 was tested against fourth instar larvae of Thaumetopoea pityocampa. The LT₅₀ and LT₉₀ of 1?×?10⁶ concentration of M. anisopliae against T. pityocampa were 3.60 and 4.11 for direct application, while these were 2.87 and 3.60?days, respectively in leaves application. The LT₅₀ and LT₉₀ of the 1?×?10⁸ concentration of the same isolate were 2.50 and 2.95?days for direct application, and 2.98 and 3.74?days for leaves application. The LT₅₀ of insect and leaves application for 1?×?10⁶ of B. bassiana were 3.75 and 3.49?days, respectively. The LT₉₀ of same concentration for insect application was 4.48?days, while LT₉₀ for leaves application was 4.63?days. Similarly, LT₅₀ of insect and leaves application for 1?×?10⁸ of B. bassiana were 3.03 and 3.31?days, while LT₉₀ were 3.68 and 4.29?days, respectively. Approximate 100% mycosis was observed in all treatments.     

The impact of naturally occurring entomopathogenic nematodes on false codling moth,Thaumatotibia leucotreta (Lepidoptera: Tortricidae), in citrus orchards

The impact of naturally occurring entomopathogenic nematodes (EPNs) on Thaumatotibia leucotreta was studied in a citrus orchard in Nelspruit, South Africa. Fruit infestation by T. leucotreta was 58.6% lower (P < 0.05) in an orchard block where EPN was conserved compared to a block where EPN was suppressed by nematicide (cadusafos) application.     

航天诱变对昆虫病原真菌的生物学效应

8个昆虫病原真菌菌株经过航天搭载后,有5个菌株的孢子在航天搭载后全部死亡,菌株M2029和MR8的存活率仅约10-7,菌株M189的存活率可达到20%以上。分离得到航天诱变的单菌落菌株,检测表明航天诱变使昆虫病原真菌的形态、生长速度、产孢量、致病力等多项生物学特性发生了不同程度的变异,变异率高,变异趋向有正负双向性。测定结果表明航天诱变菌株HM189-68s、HM189-32c、HM189-127和HM189-17的生长特性和致病力优于原始菌株。航天诱变为选育生物防治优良菌株提供了新途径。     

Use of entomopathogenic fungi combined with biorational insecticides to control Dichroplus maculipennis (Orthoptera: Acrididae: Melanoplinae) under semi-field conditions

Grasshoppers are among the invertebrate herbivores that cause most economic losses in grasslands throughout Argentina’s Pampas and parts of Patagonia. Chemical insecticides remain the sole option for grasshopper control in this area, despite being of significant environmental concern. Our aim was to evaluate the efficacy of combinations between three entomopathogenic fungi strains (Beauveria bassiana LPSc 1067 and LPSc1082), and Metarhizium anisopliae (LPSc 907), two biorational insecticides (luphenuron and methoxyfenozide), and a new synthetic chemical pesticide (rynaxypyr) in the control of the pest grasshopper Dichroplus maculipennis under field cage conditions. Fungal strains used were adjusted to 1 × 10⁸, 1 × 10⁶ and 1 × 10⁴ conidia/ml. Insecticides were tested at three concentrations: the average concentration recommended for application in the field (100%), 50% of that level and finally 25%. Combinations of the insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to D. maculipennis nymphs than any of the individual agents used alone. The three insecticides tested did not negatively affect the isolates of the two species of entomopathogenic fungi employed.     

转Cry1Ac抗虫棉对土壤虫生真菌群落的影响

利用大蜡螟Galleria mellonella L.诱菌法对转Cry1Ac抗虫棉GK-12及其亲本棉花SM-3的根系区域土壤的虫生真菌种类和数量进行监测,评价转Cry1Ac基因对棉田土壤虫生真菌的影响。实验结果显示:检测到的虫生真菌种类,在转基因棉GK-12及其亲本棉SM-3之间无显著差异,均为球孢白僵菌(Beauveria bassiana)和金龟子绿僵菌(Metarhizium anisopliae);在棉花开花初期、盛花期、结铃期或吐絮期,土壤虫生真菌数量在抗虫棉GK-12和亲本SM-3之间存在显著的差异,其他生育期无显著差异;在距棉花主根不同距离(5 cm\15 cm\25 cm)的区域,土壤虫生真菌数量和种类在抗虫棉GK-12和亲本SM-3之间无显著差异。     

Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera

Abstract:  The western corn rootworm Diabrotica virgifera virgifera Le Conte (Col., Chrysomelidae), a serious pest of maize, has been recently introduced into Europe. Several approaches for its control are presently under investigation including microbial agents. During a field survey in Hungary in 2005, naturally occurring entomopathogenic fungi were found to attack this pest. These novel isolates together with standard isolates were tested for virulence against D. v. virgifera larvae and adults. Twenty strains of Metarhizium anisopliae , Beauveria bassiana and Beauveria brongniartii were used in bioassays in the laboratory. Larvae and adults were dipped into a spore suspension with a concentration of 1 × 10⁷ conidia (con.)/ml. They were kept for 14 days at 22°C (±2°C) and 70% relative humidity. The number of infected larvae and adults were counted and infection rates were calculated. Adults were significantly more susceptible to entomopathogenic fungi than larvae. The most virulent isolate infected about 47% of larvae ( M. anisopliae Ma2277), whereas the infection rate in adults was up to 97% ( M. anisopliae Ma2275). Isolates of M. anisopliae caused significantly higher mortalities than isolates of B. brongniartii and B. bassiana . Most of the adult beetles were killed within 12 days. Isolates from D. v. virgifera were more virulent than those from other hosts.     

Persistence of Beauveria bassiana sensu lato and Metarhizium anisopliae sensu lato in Vermont (USA) forest soil

Persistence of granular formulations of Beauveria bassiana sensu lato, strains GHA726 and ERL1170, and Metarhizium anisopliae sensu lato, strains ERL824 and ERL701, applied to forest soil was documented. One formulation was prepared by producing fungi on millet and at application adding cooked, dried millet to provide additional nutrients for fungal growth. The other was made by producing fungi on corn starch ‘packing peanuts’, a biodegradable packaging material, adding additional packing peanuts as a nutrient base. The trial was conducted in three sites in a forest predominating in sugar maple (Acer saccharum) in Underhill, VT, USA. In each site, 33 dominant sugar maples were randomly selected. A 1-m² plot located 1 m from the bole of the tree was established. Soil samples were collected before application, and 1 h, 2, 4, 8, 12 and 16 wk post-application. Fungal levels were estimated based on number of colony-forming units (CFUs). A significant increase in CFUs was observed 2 wk post-application in plots treated with isolates GHA726, ERL1170 and ERL824 as a result of fungal reproduction on nutrients in the formulations. Evidence of greater persistence for the B. bassiana than the M. anisopliae isolates was observed, based on CFU levels over time. Isolates formulated with millet proliferated more than those on packing peanuts. Use of entomopathogenic fungi in forest soil has potential for managing soil-dwelling insect pests such as pear thrips, Taeniothrips inconsequens, and the black vine weevil, Otiorhynchus sulcatus, though the type of formulation and the specific isolate used must be selected carefully.     

Potential for biocontrol of house flies,Musca domestica,using fungal biopesticides

Chemical control of house flies in poultry production facilities is becoming increasingly difficult due to insecticide resistance and regulatory constraints. Biopesticides based on entomopathogenic fungi could provide an alternative approach. Here we evaluated population control potential of two fungal pathogens, Beauveria bassiana and Metarhizium anisopliae. Cohorts of adult flies were established in large plastic boxes in the laboratory and were exposed to residues of oil-formulated fungal conidia sprayed on strips of plastic sheeting attached to the box walls. Exposure to the biopesticide barrier treatments caused 100% mortality in adult populations within 8–16 days, depending on the fungal species. In contrast, control flies survived until 96–110 days. Additionally, fungal infections caused 13–20% reduction in egg viability and >70% reduction in fecundity of flies prior to death. The combined lethal and pre-lethal impacts resulted in 21- to 26-fold reduction in basic reproductive rate in the fungus-exposed populations relative to controls. Based on these promising proof-of-principle results, further research is currently under way to determine the feasibility of developing a biopesticide product for operational use.     

Effect of nutrition on growth and virulence of the entomopathogenic fungus Beauveria bassiana

Three isolates of the entomopathogen Beauveria bassiana along with one strain of Metarhizium anisopliae were cultured on seven media with different carbon/nitrogen (C/N) ratios. The effect of nutrition on virulence of the isolates was evaluated via measurement of colony growth, spore yield, germination speed, conidial C/N ratio and Pr1 (a serine protease) activity. 'Osmotic stress' medium produced the lowest colony growth with low numbers of conidia in all isolates. However, these conidia showed a high germination rate and virulence. However, conidial Pr1 activity was low in some isolates. In most but not in all cases conidia from 1% yeast extract, 2% peptone and low (10 : 1) C/N medium had higher Pr1 activity compared with conidia from other media. However, in some instances we could not conclude that there was a relationship among germination rate, conidial Pr1 activity and virulence. C/N ratio of conidia was statistically different among various media and fungal isolates. Conidia with lower C/N ratio generally produced lower LT(50) (lowest median lethal time) values (more virulent). Insect-passaged conidia from different media had lower C/N ratio compared with similar conidia from artificial cultures. Therefore, they should be more virulent than in vitro produced conidia. As germination rate, conidial Pr1 activity and C/N ratio are independent of host, it seems that host-related determinants such as insect cuticle and physiology and environmental conditions may influence host susceptibility and therefore fungal isolate virulence towards host insects.     

Effects of four commercial fungal formulations on mortality and sporulation in house flies (Musca domestica) and stable flies (Stomoxys calcitrans)

The house fly Musca domestica L. (Diptera: Muscidae) and stable fly Stomoxys calcitrans (L.) (Diptera: Muscidae) are major pests of livestock. Biological control is an important tool in an integrated control framework. Increased mortality in filth flies has been documented with entomopathogenic fungi, several strains of which are commercially available. Three strains of Beauveria bassiana (Balsamo‐Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) and one strain of Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) were tested in commercial formulations for pathogenicity against house flies and stable flies. There was a significant increase in mortality of house flies with three of the formulations, BotaniGard^® ES, Mycotrol^® O, and Met52^® EC, during days 4–9 in comparison with balEnce? and the control. In stable flies, mortality rates were highest with Met52^® EC, followed by Mycotrol^® O, BotaniGard^® ES and, finally, balEnce?. There was a significant fungal effect on sporulation in both house flies and stable flies. Product formulation, species differences and fungal strains may be responsible for some of the differences observed. Future testing in field situations is necessary. These commercial biopesticides may represent important tools in integrated fly management programmes.     

Isolation and identification of entomopathogenic nematodes from citrus orchards in South Africa and their biocontrol potential against false codling moth

A survey was conducted to determine the diversity and frequency of endemic entomopathogenic nematodes (EPN) in citrus orchards in the Western Cape, Eastern Cape and Mpumalanga provinces of South Africa. The main aim of the survey was to obtain nematodes as biological control agents against false codling moth (FCM), Thaumatotibia leucotreta, a key pest of citrus in South Africa. From a total of 202 samples, 35 (17%) tested positive for the presence of EPN. Of these, four isolates (11%) were found to be steinernematids, while 31 (89%) were heterorhabditids. Sequencing and characterisation of the internal transcribed spacer (ITS) region was used to identify all nematode isolates to species level. Morphometrics, morphology and biology of the infective juvenile (IJ) and the first-generation male were used to support molecular identification and characterisation. The Steinernema spp. identified were Steinernema khoisanae, Steinernema yirgalemense and Steinernema citrae. This is the first report of S. yirgalemense in South Africa, while for S. citrae it is the second new steinernematid to be identified from South Africa. Heterorhabditis species identified include Heterorhabditis bacteriophora, Heterorhabditis zealandica and an unknown species of Heterorhabditis. Laboratory bioassays, using 24-well bioassay disks, have shown isolates of all six species found during the survey, to be highly virulent against the last instar of FCM larvae. S. yirgalemense, at a concentration of 50 IJs/FCM larva caused 100% mortality and 74% at a concentration of 200 IJs/pupa. Using a sand bioassay, S. yirgalemense gave 93% control of cocooned pupae and emerging moths at a concentration of 20 IJs/cm². This is the first report on the potential use of EPN to control the soil-borne life stages of FCM, which includes larvae, pupae and emerging moths. It was shown that emerging moths were infected with nematodes, which may aid in control and dispersal.     

Selection of promising fungal biological control agent of the western flower thrips Frankliniella occidentalis (Pergande)

Aims: Larval stages of Frankliniella occidentalis are known to be refractory to fungal infection compared with the adult stage. The objective of this study was to identify promising fungal isolate(s) for the control of larval stages of F. occidentalis. Methods and Results: Ten isolates of Metarhizium anisopliae and eight of Beauveria bassiana were screened for virulence against second‐instar larvae of F. occidentalis. Conidial production and genetic polymorphism were also investigated. Metarhizium anisopliae isolates ICIPE 7, ICIPE 20, ICIPE 69 and ICIPE 665 had the shortest LT₅₀ values of 8·0–8·9 days. ICIPE 69, ICIPE 7 and ICIPE 20 had the lowest LC₅₀ values of 1·1 × 10⁷, 2·0 × 10⁷ and 3·0 × 10⁷ conidia ml^?1, respectively. Metarhizium anisopliae isolate ICIPE 69 produced significantly more conidia than M. anisopliae isolates ICIPE 7 and ICIPE 20. Internally transcribed spacers sequences alignment showed differences in nucleotides composition, which can partly explain differences in virulence. Conclusion: These results coupled with the previous ones on virulence and field efficacy against other species of thrips make M. anisopliae isolate ICIPE 69 a good candidate. Significance and Impact of the Study: Metarhizium anisopliae isolate ICIPE 69 can be suggested for development as fungus‐based biopesticide for thrips management.     

Culture conditions affect virulence and production of insect toxic proteins in the entomopathogenic fungus Metarhizium anisopliae

Conidial spores are often used as the infectious agent during insect biocontrol applications of entomopathogenic fungi. Here we show differential virulence of conidia derived from Metarhizium anisopliae strain EAMa 01/58-Su depending upon the solid substrata used for cultivation, where LC₅₀ values differed by up to ~10-fold (5.3×10⁶?4.5×10⁵ conidia/ml) and LT₅₀ values by ~40% (9.8?7.1 d). This fungal strain is also known to secrete proteins that are toxic towards adult Mediterranean fruit flies, Ceratitis capitata, and the Greater wax moth, Galleria mellonella, larvae. In vitro production and intrahemoceol injection using G. mellonella as the host was used to test fractions during purification of the protein toxins, demonstrating that they elicited defence-related responses including melanisation and tissue necrosis. Production of these proteins/peptides along with a number of potential cuticle degrading enzymes was confirmed both in vitro and during the infection process (in vivo). Two-dimensional gel electrophoresis, followed by gel elution and bioassay, was used to identify at least three proteins or peptides (molecular mass=11, 15 and 15 kDa) as mediating the observed insect toxicity. These data demonstrate that in vitro screening for insect toxins can mimic in vivo (i.e. during the infection process) secretion and applies the use of proteomics to invertebrate pathology.     

Virulence of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against red palm weevil,Rhynchophorus ferrugineus (Olivier)

Nineteen different isolates of the entomopathogenic fungi Beauveria bassiana sensu lato (s.l.) and Metarhizium anisopliae s.l. (Ascomycota: Hypocreales), recovered from different soil samples (field crops, fruit orchards, vegetable fields and forests) and insect cadavers were tested against Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) at two different spore concentrations (1 × 10⁷ and 1 × 10⁸ conidia mL^?1). Three isolates of B. bassiana and two of M. anisopliae gave >88 % larval and >75 % adult mortality of R. ferrugineus on their highest dose rate respectively. More sporulating cadavers (mycosis) resulted from a high dose rate compared to low dose on both life stages of R. ferrugineus. The current study confirmed the lethal action of B. bassiana and M. anisopliae isolates with mortality levels usually directly proportional to the conidial concentration. This study further confirmed that the isolates recovered from R. ferrugineus dead cadavers gave more mortality compared to the other sources. In the virulence assay two isolates of B. bassiana caused the highest percentage of both larval and adult mortality at all exposure intervals which suggest that they may be the most promising for use in sustainable management programs aimed at microbial control in date palm orchards.     

Mitochondrial evolution in the entomopathogenic fungal genus Beauveria

Species in the fungal genus Beauveria are pathogens of invertebrates and have been commonly used as the active agent in biopesticides. After many decades with few species described, recent molecular approaches to classification have led to over 25 species now delimited. Little attention has been given to the mitochondrial genomes of Beauveria but better understanding may led to insights into the nature of species and evolution in this important genus. In this study, we sequenced the mitochondrial genomes of four new strains belonging to Beauveria bassiana, Beauveria caledonica and Beauveria malawiensis, and compared them to existing mitochondrial sequences of related fungi. The mitochondrial genomes of Beauveria ranged widely from 28,806 to 44,135 base pairs, with intron insertions accounting for most size variation and up to 39% (B. malawiensis) of the mitochondrial length due to introns in genes. Gene order of the common mitochondrial genes did not vary among the Beauveria sequences, but variation was observed in the number of transfer ribonucleic acid genes. Although phylogenetic analysis using whole mitochondrial genomes showed, unsurprisingly, that B. bassiana isolates were the most closely related to each other, mitochondrial codon usage suggested that some B. bassiana isolates were more similar to B. malawiensis and B. caledonica than the other B. bassiana isolates analyzed.     

Laboratory and glasshouse evaluation of entomopathogenic fungi against the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), on tomato, Lycopersicon esculentum

Forty isolates of entomopathogenic fungi from six genera were assessed against the two-spotted spider mite, Tetranychus urticae, in a single dose, direct application laboratory bioassay on tomato leaflets. Only three isolates caused greater mortality than the control: these were Metarhizium anisopliae 442.99, Hirsutella spp. 457.99, and Verticillium lecanii 450.99. These isolates were assessed in a multiple dose bioassay, together with three isolates cultured from commercial biopesticides as follows: Beauveria bassiana 432.99 (cultured from 'Naturalis-L', Troy Biosciences, Phoenix, TX, USA); Hirsutella thompsonii 463.99 (cultured from 'Mycar', Abbott Laboratories USA); and V. lecanii 19.79 (used in 'Mycotal' Koppert BV, The Netherlands). Beauveria bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, and V. lecanii 450.99 were all pathogenic to T. urticae in this bioassay. In addition, it was found that the mortality caused by B. bassiana 432.99 and Naturalis-L was increased when the mites were exposed to tomato leaflets sprayed previously with conidia suspensions, compared to spraying the mites directly. In a glasshouse experiment, sprays of B. bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, V. lecanii 450.99 and Naturalis-L reduced T. urticae populations in a tomato crop grown according to commercial practice. Naturalis-L reduced T. urticae numbers by up to 97%. In a second glasshouse experiment, single sprays of Naturalis-L and the acaricide fenbutatin oxide (Torq) were compared as supplementary treatments to release of the predatory mite, Phytoseiulus persimilis. Supplementary sprays of fenbutatin oxide reduced the numbers of T. urticae nymphs (80% reduction), while Naturalis-L reduced numbers of T. urticae adults, nymphs and eggs (98% reduction in all three cases). It is concluded that Naturalis-L has the potential to be used against T. urticae on glasshouse tomato crops.     

Biological control of insects in Brazil and China: history,current programs and reasons for their successes using entomopathogenic fungi

Brazil and China have been successful in the use of microbial control methods to manage several agricultural and forest insects. In both countries, entomopathogenic fungi (EF) have been used for pest management since the 1970s. However, EF production and commercialization have not been constant in either country. Several companies and cooperatives suspended their activities or shut down from the 1970s to the 1990s. This was due to loss of confidence in available mycoinsecticides by Brazilian farmers or due to reduced involvement and government subsidies for biological control in China; and, consequently, mycoinsecticides were largely replaced by inexpensive chemical insecticides. Starting in the 1990s and continuing until today, however, new Brazilian and Chinese private companies have arisen. In Brazil, the area treated with M. anisopliae for spittlebug control alone is estimated to be approximately one million hectares in 2008, 75% of which was for control of spittlebugs in sugarcane plantations and the remainder for spittlebugs in pasture grass (primarily Brachiaria spp.) and other smaller programs. In China, the fungus Beauveria bassiana was used annually in 0.8–1.3 million ha until the 1980s. Several factors were important for the success of these programs, such as: governmental support (at least during the initial steps of biocontrol programs); availability of indigenous virulent fungal isolates; low-cost substrates for mass production; retail prices of mycoinsecticides lower than their chemical counterparts; and sale by contract which allows the products to be immediately available for use, rather than stored. In this report, we discuss the current biocontrol programs using insect fungi in these two developing countries, as well as the future and main challenges they must face to further encourage the adoption of mycoinsecticides.     

Auto-dissemination of commercially available fungal pathogens in a laboratory assay for management of the brown dog tick Rhipicephalus sanguineus

Rhipicephalus sanguineus is a canine tick that infests dogs throughout the world and is frequently found in homes and dog kennels. Management of this tick species is complicated by the presence of resistance to commonly utilized acaricides. Fungal formulations could provide a valuable alternative tool for management and are especially relevant indoors where detrimental environmental effects on fungal spores are of less concern. Two commercially available fungal formulations, one containing Metarhizium anisopliae and the other containing Beauveria bassiana, were compared for time to death and sporulation in nymphal ticks exposed for 60 min in treated filter paper packets. Beauveria bassiana exposure killed ticks faster than M. anisopliae exposure and B. bassiana was more likely to sporulate on tick cadavers than M. anisopliae. To determine whether infected ticks could disseminate fungus to their conspecifics, ticks were marked and treated with fungus before being placed with untreated ticks. Fungus was successfully transmitted from treated to untreated ticks. Mortality of ticks exposed to B. bassiana-exposed conspecifics occurred sooner than for those exposed to M. anisopliae-exposed conspecifics, indicating faster dissemination in the former. Therefore, although both formulations resulted in decreased longevity of ticks compared with the controls, the B. bassiana formulation holds the most promise for direct or indirect application with respect to brown dog tick management.     

Effect of entomopathogenic fungi upon adults of Stomoxys calcitrans and Musca domestica (Diptera: Muscidae)

The pathogenicity and virulence of 10 isolates of entomopathogenic fungi from the soil of lodging pens of dairy production units in Aguascalientes, Mexico, on adults of Stomoxys calcitrans and Musca domestica were determined. All isolates were pathogenic when exposed by aspersion to a concentration of 1×10⁸ conidia/ml, causing between 20.3 and 91.7% mortality in S. calcitrans and between 31 and 91.7% in M. domestica at 7 days post-exposure; in S. calcitrans isolates of Beauveria bassiana (Bb114) and Metarhizium anisopliae (Ma135), sensu lato, were the most noteworthy as mortality reached above 90% with an LC₅₀ of 3.5×10⁵ conidia/ml for Bb114, while for Ma135 reached 1.6×10⁴ conidia/ml. In M. domestica Ma134 and Ma135 showed mortality above 90% with an LC₅₀ of 4.3×10⁴ and 1.4×10⁵ conidia/ml, respectively.